The information I have says that s 70's should be 1 inch wider than those in a 68. A 68 should measure 60 inches from drum to drum. There are a few other rears that will fit, but I don't have the information anymore. None of them are newer though. I think a 60's nova rear will work. Hot Rod had an article a few years back, but I no longer have it. A 60's mustang 9 inch is also the same width if I remember correctly. Also I think a G.T.O rear will work if you change the mounts. Sorry I couldn't give you anymore definate answers.